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CN-122027409-A - Method for estimating carrier frequency of underwater acoustic quaternary frequency shift keying signal

CN122027409ACN 122027409 ACN122027409 ACN 122027409ACN-122027409-A

Abstract

The invention discloses a carrier frequency estimation method of an underwater sound quaternary frequency shift keying signal, which carries out periodic graph method power spectrum estimation on the underwater sound signal identified as quaternary frequency shift keying to find four frequency points with strongest energy, and sorts the four frequency points into a first frequency point, a second frequency point, a third frequency point and a fourth frequency point according to the order from small to large, and calculates the difference value of adjacent frequency points after sorting to be the first difference value, the second difference value and the third difference value. The carrier frequency estimation method of the underwater acoustic quaternary frequency shift keying signal is based on the fact that the identified communication signal is the quaternary frequency shift keying signal, so that the carrier frequency estimation method provided by the invention only aims at the situation that the power spectrum frequency of a periodic chart method is not faded or faded, when two frequencies or more frequencies are missing, the signal can be directly identified as other signals, the process can not be entered, and the effects of minimum calculated amount, simplest realization and highest estimation precision are achieved.

Inventors

  • CHEN YONG
  • WU XIONGBIAO
  • HU YUNHAI
  • Wei Miling
  • SUN GUN
  • Mei Junxi

Assignees

  • 中海油深圳海洋工程技术服务有限公司

Dates

Publication Date
20260512
Application Date
20260120

Claims (7)

  1. 1. A method for estimating carrier frequency of underwater acoustic quaternary frequency shift keying signal is characterized in that, Performing periodic graph method power spectrum estimation on the underwater sound signal identified as quaternary frequency shift keying to find four frequency points with strongest energy; and sorting the frequency points into a first frequency point, a second frequency point, a third frequency point and a fourth frequency point according to the sequence from small to large, and calculating the difference value of the adjacent frequency points after sorting to be the first difference value, the second difference value and the third difference value.
  2. 2. The method of claim 1, wherein if the values of the first difference, the second difference, and the third difference have approximate relationships, the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4.
  3. 3. The method for estimating carrier frequency of four-ary frequency shift keying signal according to claim 1, wherein if the values of the first difference, the second difference and the third difference have no approximate relationship, three frequency points with strongest power spectrum energy of the periodic graph method are found, the first frequency point, the second frequency point and the third frequency point are ordered in the order from small to large, and the difference between the adjacent ordered frequency points is calculated, wherein the larger difference is set as the first difference, and the smaller difference is set as the second difference.
  4. 4. The method of claim 1, wherein if the value of the first difference is equal to about 2 times of the second difference, interpolation is performed at the center of the first difference, and the frequency corresponding to the interpolation position is the fourth frequency, and the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4.
  5. 5. The method for estimating carrier frequency of four-ary frequency shift keying signal according to claim 1, wherein if the first difference value and the second difference value have no relation of 2 times approximation, the second difference value obtained by subtracting 1.5 times from the minimum value of the first frequency point, the second frequency point and the third frequency point is taken to the first power in the frequency band range of subtracting 0.5 times from the minimum value of the first frequency point, the second frequency point and the third frequency point, and the second power in the frequency band range of adding 0.5 times to the maximum value of the first frequency point, the second frequency point and the third frequency point is compared.
  6. 6. The method of claim 5, wherein if the first power is greater than the second power, the minimum value of the first frequency point, the second frequency point, and the third frequency point minus the second difference value is taken as the fourth frequency point, and the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4.
  7. 7. The method of claim 5, wherein if the first power is smaller than the second power, the maximum value of the first frequency point, the second frequency point, and the third frequency point plus the second difference value is taken as the fourth frequency point, and the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4.

Description

Method for estimating carrier frequency of underwater acoustic quaternary frequency shift keying signal Technical Field The invention belongs to the technical field of offshore oil engineering, and particularly relates to a method for estimating carrier frequency of an underwater acoustic quaternary frequency shift keying signal. Background The underwater acoustic communication signal reconnaissance technology mainly comprises four aspects of underwater acoustic communication signal blind detection, underwater acoustic communication signal modulation type identification, underwater acoustic communication signal carrier frequency estimation and underwater communication signal interference striking, wherein the carrier frequency estimation technology is used as a third link of the underwater acoustic communication reconnaissance technology, is used for estimating the carrier frequency of an intercepted signal on the basis that the underwater acoustic communication signal has identified the intercepted signal modulation type, and is also a precondition of the accurate interference striking of the underwater acoustic communication signal in a fourth link. Only if the carrier frequency of the signal is accurately estimated, reliable information can be provided for commanders, and accurate interference on the enemy underwater acoustic communication equipment can be completed, so that the enemy underwater acoustic communication equipment loses communication capability. Different from a wireless channel, due to the complexity of the underwater acoustic channel, the frequency of the intercepted underwater acoustic quaternary frequency shift keying signal often has frequency selective fading, so that the carrier frequency estimation of the underwater acoustic quaternary frequency shift keying signal becomes difficult, the traditional carrier frequency estimation method of the quaternary frequency shift keying signal has poor effect under the underwater acoustic channel, and the accuracy of the frequency result obtained by estimation is low. Therefore, there is a need to design a carrier frequency estimation method for an underwater acoustic quaternary frequency shift keying signal, which solves the above-mentioned problems. Disclosure of Invention In order to solve the technical problems that the traditional quaternary frequency shift keying signal carrier frequency estimation method mentioned in the background technology has poor effect under the underwater acoustic channel and the accuracy of the frequency result obtained by estimation is low, the invention provides the underwater acoustic quaternary frequency shift keying signal carrier frequency estimation method so as to solve the problems existing in the background technology. In order to achieve the above purpose, the specific technical scheme of the method for estimating the carrier frequency of the underwater acoustic quaternary frequency shift keying signal of the invention is as follows: a carrier frequency estimation method of underwater acoustic quaternary frequency shift keying signals carries out periodic chart method power spectrum estimation on the underwater acoustic signals identified as quaternary frequency shift keying to find out four frequency points with strongest energy; and sorting the frequency points into a first frequency point, a second frequency point, a third frequency point and a fourth frequency point according to the sequence from small to large, and calculating the difference value of the adjacent frequency points after sorting to be the first difference value, the second difference value and the third difference value. Further, if the values of the first difference, the second difference and the third difference have an approximate relationship, the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4. Further, if the values of the first difference value, the second difference value and the third difference value have no approximate relation, three frequency points with the strongest power spectrum energy of the periodic graph method are found, the first frequency point, the second frequency point and the third frequency point are sequenced in the sequence from small to large, and the difference values of adjacent frequency points after sequencing are calculated, wherein the larger difference value is set as the first difference value, and the smaller difference value is set as the second difference value. Further, if the value of the first difference is approximately equal to the second difference which is 2 times, interpolation is performed at the center of the first difference, and the frequency corresponding to the interpolation position is the fourth frequency, so that the carrier frequency estimation result is (first frequency point+second frequency point+third frequency point+fourth frequency point)/4. Further, if the first difference value and